My fave has always been:

Holy jumping mother o’God in a sidecar with chocolate jimmies and a lobster bib!

From Sam & Max: Freelance Police

I never knew Sam & Max had such a career! A friend gave me a copy in high school and I never heard or saw anything else Sam & Max until today.

I love this one...

It is a fool's prerogative to utter truths that no one else will speak.

it's from the sandman with shakespeare- the first one.

"Pear pimples for hairy fishnuts."

"So, I guess you know I've been worried about you."
--Death, to her brother Dream, from Sandman

From Atomic Robo, after he's congratulated for destroying giant attacking ants:

"I just used my violence on them."

Once you realize what a joke everything is, being the Comedian is the only thing that makes sense.

-The Comedian, Watchmen.

(I need to read Sandman sometime)

"The devil made me do it.
I have never made one of them do anything. Never.
They live their own lives. I do not live their lives for them.
They belong to themselves, they just hate to face up to it."

-Lucifer in Seasons of Mists/Sandman

Also, it's snorts and giggles everytime Beast (X-Men) goes "Oh my stars and garters!"